Patent application title: SYSTEM IDENTIFICATION DEVICE

Abstract:

This invention provides a system identification device capable of
identifying an inertia moment in an electric motor and a viscous friction
through only a very small operation. System identification device
provides a position amplitude calculator for outputting a position
amplifier; a position torque command integral value multiplier for
outputting a position torque command integral value multiplication value;
a position torque command integral value average calculator for inputting
the position torque command integral value multiplication value and then
outputting an average of a position torque command integral value; a
speed torque command integral value multiplier for outputting a speed
torque command integral value multiplication value; a speed torque
command integral value average calculator for inputting the speed torque
command integral value multiplication value and then outputting an
average of a speed torque command integral value; and a first inertia
moment and viscous friction calculator for calculating identification
values of inertia moment and viscous friction from the position
amplitude, the average of the position torque command integral value and
the average of the speed torque command integral value.

Claims:

1. A system identification device comprising:a speed command generator for
outputting a speed command;a differentiator for inputting a position of
an electric motor detected by a position detector and then outputting a
speed;a speed controller for inputting the speed command and the speed
and then outputting a torque command;a torque controller for inputting
the torque command and then driving the electric motor with an electric
motor current; andan inertia moment and viscous friction identifier for
inputting the torque command, the position and the speed, and then
calculating and outputting identification values of an inertia moment in
the electric motor and a viscous friction,wherein the inertia moment and
viscous friction identifier includes:a position amplitude calculator for
inputting the position and then calculating and outputting a position
amplitude to be an amplitude of a fundamental frequency component of the
input signal;a position torque command integral value multiplier for
inputting the position and the torque command, and then calculating and
outputting a position torque command integral value multiplication value
to be a multiplication value of the fundamental frequency component of
the position and an Nth-order time integral value of the torque command,
wherein N is set to a natural number including zero;a position torque
command integral value average calculator for inputting the position
torque command integral value multiplication value and then calculating
and outputting an average of a position torque command integral value to
be a one-cycle average of the input signal;a speed torque command
integral value multiplier for inputting the torque command and the speed,
and then calculating and outputting a speed torque command integral value
multiplication value to be a multiplication value of the fundamental
frequency component of the speed and the Nth-order time integral value of
the torque command;a speed torque command integral value average
calculator for inputting the speed torque command integral value
multiplication value, and then calculating and outputting an average of a
speed torque command integral value to be a one-cycle average of the
input signal; anda first inertia moment and viscous friction calculator
for inputting the position amplitude, the average of the position torque
command integral value and the average of the speed torque command
integral value, and then calculating and outputting the identification
values of the inertia moment and the viscous friction.

2. A system identification device comprising:a position command generator
for outputting a position command;a differentiator for inputting a
position of an electric motor detected by a position detector and then
outputting a speed;a position controller for inputting the position
command and the position and then outputting a speed command;a speed
controller for inputting the speed command and the speed and then
outputting a torque command;a torque controller for inputting the torque
command and then driving the electric motor with an electric motor
current; andan inertia moment and viscous friction identifier for
inputting the torque command, the position and the speed, and then
calculating and outputting identification values of an inertia moment in
the electric motor and a viscous friction, wherein the inertia moment and
viscous friction identifier includes:a position amplitude calculator for
inputting the position and then calculating and outputting a position
amplitude to be an amplitude of a fundamental frequency component of the
input signal;a position torque command integral value multiplier for
inputting the position and the torque command, and then calculating and
outputting a position torque command integral value multiplication value
to be a multiplication value of the fundamental frequency component of
the position and an Nth-order time integral value of the torque command,
wherein N is set to a natural number including zero;a position torque
command integral value average calculator for inputting the position
torque command integral value multiplication value and then calculating
and outputting an average of a position torque command integral value to
be a one-cycle average of the input signal;a speed torque command
integral value multiplier for inputting the torque command and the speed,
and then calculating and outputting a speed torque command integral value
multiplication value to be a multiplication value of the fundamental
frequency component of the speed and the Nth-order time integral value of
the torque command;a speed torque command integral value average
calculator for inputting the speed torque command integral value
multiplication value, and then calculating and outputting an average of a
speed torque command integral value to be a one-cycle average of the
input signal; anda first inertia moment and viscous friction calculator
for inputting the position amplitude, the average of the position torque
command integral value and the average of the speed torque command
integral value, and then calculating and outputting the identification
values of the inertia moment and the viscous friction.

3. The system identification device according to claim 1 or 2, wherein the
position torque command integral value multiplier and the speed torque
command integral value multiplier set the Nth-order time integral value
of the torque command to be a 0th-order time integral value of the torque
command.

4. The system identification device according to claim 1 or 2, wherein the
position torque command integral value multiplier and the speed torque
command integral value multiplier set the Nth-order time integral value
of the torque command to be a 1st-order time integral value of the torque
command.

5. The system identification device according to claim 1 or 2, wherein the
position amplitude calculator calculates a position fundamental frequency
component to be the fundamental frequency component of the position, and
then calculates and outputs the position amplitude using a Fourier
transformation,the position torque command integral value multiplier
calculates a position fundamental frequency component to be the
fundamental frequency component of the position and a torque command
fundamental frequency component to be the fundamental frequency component
of the torque command using the Fourier transformation, and then
calculates and outputs the position torque command integral value
multiplication value to be a multiplication value of the position
fundamental frequency component and an Nth-order time integral value of
the torque command fundamental frequency component, andthe speed torque
command integral value multiplier calculates a torque command fundamental
frequency component to be the fundamental frequency component of the
torque command and a speed fundamental frequency component to be the
fundamental frequency component of the speed using the Fourier
transformation, and then calculates and outputs the speed torque command
integral value multiplication value to be a multiplication value of the
Nth-order time integral value of the torque command fundamental frequency
component and the speed fundamental frequency component.

6. The system identification device according to claim 1 or 2, wherein the
position amplitude calculator calculates a position fundamental frequency
component to be the fundamental frequency component of the position, and
then calculates and outputs the position amplitude using a band-pass
filter,the position torque command integral value multiplier calculates a
position fundamental frequency component to be the fundamental frequency
component of the position and a torque command fundamental frequency
component to be the fundamental frequency component of the torque command
using the band-pass filter, and then calculates and outputs the position
torque command integral value multiplication value to be a multiplication
value of the position fundamental frequency component and an Nth-order
time integral value of the torque command fundamental frequency
component, andthe speed torque command integral value multiplier
calculates a torque command fundamental frequency component to be the
fundamental frequency component of the torque command and a speed
fundamental frequency component to be the fundamental frequency component
of the speed using the band-pass filter, and then calculates and outputs
the speed torque command integral value multiplication value to be a
multiplication value of the Nth-order time integral value of the torque
command fundamental frequency component and the speed fundamental
frequency component.

7. A system identification device comprising:a speed command generator for
outputting a speed command;a differentiator for inputting a position of
an electric motor detected by a position detector and then outputting a
speed;a speed controller for inputting the speed command and the speed
and then outputting a torque command;a torque controller for inputting
the torque command and then driving the electric motor with an electric
motor current; andan inertia moment and viscous friction identifier for
inputting the torque command, the position and the speed, and then
calculating and outputting identification values of an inertia moment in
the electric motor and a viscous friction,wherein the inertia moment and
viscous friction identifier includes:a position amplitude calculator for
inputting the position and then calculating and outputting a position
amplitude to be an amplitude of a fundamental frequency component of the
input signal; anda second inertia moment and viscous friction calculator
for inputting the position amplitude and the torque command, and
calculating a Fourier coefficient of the torque command by a Fourier
transformation, and then calculating and outputting the identification
values of the inertia moment and the viscous friction using the position
amplitude and the Fourier coefficient.

8. A system identification device comprising:a position command generator
for outputting a position command;a differentiator for inputting a
position of an electric motor detected by a position detector and then
outputting a speed;a position controller for inputting the position
command and the position and then outputting a speed command;a speed
controller for inputting the speed command and the speed and then
outputting a torque command;a torque controller for inputting the torque
command and then driving the electric motor with an electric motor
current; andan inertia moment and viscous friction identifier for
inputting the torque command, the position and the speed, and then
calculating and outputting identification values of an inertia moment in
the electric motor and a viscous friction,wherein the inertia moment and
viscous friction identifier includes:a position amplitude calculator for
inputting the position and then calculating and outputting a position
amplitude to be an amplitude of a fundamental frequency component of the
input signal; anda second inertia moment and viscous friction calculator
for inputting the position amplitude and the torque command, and
calculating a Fourier coefficient of the torque command by a Fourier
transformation, and then calculating and outputting the identification
values of the inertia moment and the viscous friction using the position
amplitude and the Fourier coefficient.

9. The system identification device according to claim 1, whereinwhen a
fundamental frequency of the speed command is represented by ω, a
torque command fundamental frequency component is represented by Tref0, a
position fundamental frequency component is represented by θ0, and
the position amplitude is represented by A,the first inertia moment and
viscous friction calculator calculates the identification values of the
inertia moment J in the electric motor and the viscous friction D in
accordance with the following Equations (1) and (2): J = - 2 T
ref 0 θ 0 _ ω 2 A 2 ( 1 )
D = 2 T ref 0 θ . 0 _ ω 2 A
2 ( 2 ) ##EQU00023##

10. The system identification device according to claim 2, whereinwhen a
fundamental frequency of the position command is represented by ω,
a torque command fundamental frequency component is represented by Tref0,
a position fundamental frequency component is represented by θ0,
and the position amplitude is represented by A,the first inertia moment
and viscous friction calculator calculates the identification values of
the inertia moment J in the electric motor and the viscous friction D in
accordance with the following Equations (1) and (2): J = - 2 T
ref 0 θ 0 _ ω 2 A 2 ( 1 )
D = 2 T ref 0 θ . 0 _ ω 2 A
2 ( 2 ) ##EQU00024##

11. The system identification device according to claim 1, whereinwhen a
fundamental frequency of the speed command is represented by ω, a
torque command fundamental frequency component is represented by Tref0, a
position fundamental frequency component is represented by θ0, and
the position amplitude is represented by A,the first inertia moment and
viscous friction calculator calculates the identification values of the
inertia moment J in the electric motor and the viscous friction D in
accordance with the following Equations (3) and (4): J = 2
∫ T ref 0 t θ . 0 _ ω 2
A 2 ( 3 ) D = 2 ∫ T ref 0 t
θ 0 _ A 2 ( 4 ) ##EQU00025##

12. The system identification device according to claim 2, whereinwhen a
fundamental frequency of the position command is represented by ω,
a torque command fundamental frequency component is represented by Tref0,
a position fundamental frequency component is represented by θ0,
and the position amplitude is represented by A,the first inertia moment
and viscous friction calculator calculates the identification values of
the inertia moment J in the electric motor and the viscous friction D in
accordance with the following Equations (3) and (4): J = 2
∫ T ref 0 t θ . 0 _ ω 2
A 2 ( 3 ) D = 2 ∫ T ref 0 t
θ 0 _ A 2 ( 4 ) ##EQU00026##

13. The system identification device according to claim 7, whereinwhen a
fundamental frequency of the speed command is represented by ω, the
position amplitude is represented by A, a Fourier coefficient of a
fundamental frequency cosine component of the torque command is
represented by a0, and a Fourier coefficient of a fundamental frequency
sine component of the torque command is represented by b0,the second
inertia moment and viscous friction calculator calculates the
identification values of the inertia moment J in the electric motor and
the viscous friction D in accordance with the following Equations (5) and
(6): J = - a 0 ω 2 A ( 5 ) D = - b 0
ω A ( 6 ) ##EQU00027##

14. The system identification device according to claim 8, whereinwhen a
fundamental frequency of the speed command is represented by ω, the
position amplitude is represented by A, a Fourier coefficient of a
fundamental frequency cosine component of the torque command is
represented by a0, and a Fourier coefficient of a fundamental frequency
sine component of the torque command is represented by b0,the second
inertia moment and viscous friction calculator calculates the
identification values of the inertia moment J in the electric motor and
the viscous friction D in accordance with the following Equations (5) and
(6): J = - a 0 ω 2 A ( 5 ) D = - b 0
ω A ( 6 ) ##EQU00028##

Description:

TECHNICAL FIELD

[0001]The present invention relates to a system identification device for
identifying an inertia moment in an electric motor and a viscous
friction.

BACKGROUND ART

[0002]A system identification device according to the related art
identifies an inertia moment of a control target by dividing, by an
integral time of an integrator, a steady-state value of a command torque
difference Nth-order integral value to be an Nth-order time integral
value of a signal obtained by subtracting an equivalent IP control system
command torque from a PI control system command torque (see e.g., Patent
Document 1).

[0003]FIG. 8 is a block diagram showing a system identification device
according to the related art.

[0005]A structure and operation of the system identification device
according to the related art will be described below with reference to
FIG. 8.

[0006]The first mixer 801 outputs a signal obtained by subtracting a speed
from a speed command. The proportional amplifier 802 inputs the output of
the first mixer 801 and outputs a signal obtained by amplifying the input
signal. The integrator 803 inputs the output of the proportional
amplifier 802 and then outputs a PI control system command torque to be a
value obtained by adding the input signal and a 1st-order time integral
value amplification value of the input signal. The second mixer 804
outputs a value obtained by adding the PI control system command torque
and an output of the control target Coulomb friction 806. The control
target 805 inputs the output of the second mixer 804 and then outputs the
speed. The control target Coulomb friction 806 inputs the speed and then
outputs a signal having a constant absolute value and a reverse sign to
that of the input signal. The first order lag filter 807 inputs the PI
control system command torque and then outputs an equivalent IP control
system command torque. The Nth-order integration 808 inputs a signal
obtained by subtracting the equivalent IP control system command torque
from the PI control system command torque and then outputs a command
torque difference Nth-order integral value to be an Nth-order time
integral value of the input signal.

[0007]As described the above structure, a steady-state value of the
command torque difference Nth-order integral value for the speed command
having a constant sign is divided by the integral time of the integrator
803 to identify an inertia moment of the control target 805.

[0008]However, the system identification device according to the related
art uses a speed command having a constant sign. For this reason, there
is a problem in that a sufficiently large movable range is required for
identifying an inertia moment, and an inertia moment of an electric motor
having a movable range restricted cannot be identified.

[0009]In consideration of the above problem, an object of the invention
provides a system identification device capable of suppressing the
influence of a constant torque disturbance and suppressing the influence
of a noise in a torque command for a speed control system and a position
control system having any linear control law using any periodic speed
command or periodic position command, thereby identifying an inertia
moment in an electric motor and a viscous friction through only a very
small operation in a short time. Furthermore, an object of the invention
provides a system identification device capable of suppressing the
influence of a constant torque disturbance for any linear control law
using any periodic speed command or periodic position command by only a
simple calculation, thereby identifying an inertia moment in an electric
motor and a viscous friction through only a very small operation in a
short time.

Means for Solving the Problems

[0010]In order to solve the problems, a first aspect of the invention is
directed to a system identification device comprising:

[0011]a speed command generator for outputting a speed command;

[0012]a differentiator for inputting a position of an electric motor
detected by a position detector and then outputting a speed;

[0013]a speed controller for inputting the speed command and the speed and
then outputting a torque command;

[0014]a torque controller for inputting the torque command and then
driving the electric motor with an electric motor current; and

[0015]an inertia moment and viscous friction identifier for inputting the
torque command, the position and the speed, and then calculating and
outputting identification values of an inertia moment in the electric
motor and a viscous friction,

[0017]a position amplitude calculator for inputting the position and then
calculating and outputting a position amplitude to be an amplitude of a
fundamental frequency component of the input signal;

[0018]a position torque command integral value multiplier for inputting
the position and the torque command, and then calculating and outputting
a position torque command integral value multiplication value to be a
multiplication value of the fundamental frequency component of the
position and an Nth-order time integral value of the torque command,
wherein N is set to a natural number including zero;

[0019]a position torque command integral value average calculator for
inputting the position torque command integral value multiplication value
and then calculating and outputting an average of a position torque
command integral value to be a one-cycle average of the input signal;

[0020]a speed torque command integral value multiplier for inputting the
torque command and the speed, and then calculating and outputting a speed
torque command integral value multiplication value to be a multiplication
value of the fundamental frequency component of the speed and the
Nth-order time integral value of the torque command;

[0021]a speed torque command integral value average calculator for
inputting the speed torque command integral value multiplication value,
and then calculating and outputting an average of a speed torque command
integral value to be a one-cycle average of the input signal; and

[0022]a first inertia moment and viscous friction calculator for inputting
the position amplitude, the average of the position torque command
integral value and the average of the speed torque command integral
value, and then calculating and outputting the identification values of
the inertia moment and the viscous friction.

[0023]Moreover, a second aspect of the invention is directed to a system
identification device comprising:

[0024]a position command generator for outputting a position command;

[0025]a differentiator for inputting a position of an electric motor
detected by a position detector and then outputting a speed;

[0026]a position controller for inputting the position command and the
position and then outputting a speed command;

[0027]a speed controller for inputting the speed command and the speed and
then outputting a torque command;

[0028]a torque controller for inputting the torque command and then
driving the electric motor with an electric motor current; and

[0029]an inertia moment and viscous friction identifier for inputting the
torque command, the position and the speed, and then calculating and
outputting identification values of an inertia moment in the electric
motor and a viscous friction,

[0031]a position amplitude calculator for inputting the position and then
calculating and outputting a position amplitude to be an amplitude of a
fundamental frequency component of the input signal;

[0032]a position torque command integral value multiplier for inputting
the position and the torque command, and then calculating and outputting
a position torque command integral value multiplication value to be a
multiplication value of the fundamental frequency component of the
position and an Nth-order time integral value of the torque command,
wherein N is set to a natural number including zero;

[0033]a position torque command integral value average calculator for
inputting the position torque command integral value multiplication value
and then calculating and outputting an average of a position torque
command integral value to be a one-cycle average of the input signal;

[0034]a speed torque command integral value multiplier for inputting the
torque command and the speed, and then calculating and outputting a speed
torque command integral value multiplication value to be a multiplication
value of the fundamental frequency component of the speed and the
Nth-order time integral value of the torque command;

[0035]a speed torque command integral value average calculator for
inputting the speed torque command integral value multiplication value,
and then calculating and outputting an average of a speed torque command
integral value to be a one-cycle average of the input signal; and

[0036]a first inertia moment and viscous friction calculator for inputting
the position amplitude, the average of the position torque command
integral value and the average of the speed torque command integral
value, and then calculating and outputting the identification values of
the inertia moment and the viscous friction.

[0037]Furthermore, a third aspect of the invention is directed to the
system identification device according to the first or second aspect of
the invention, wherein the position torque command integral value
multiplier and the speed torque command integral value multiplier set the
Nth-order time integral value of the torque command to be a 0th-order
time integral value of the torque command.

[0038]In addition, a fourth aspect of the invention is directed to the
system identification device according to the first or second aspect of
the invention, the position torque command integral value multiplier and
the speed torque command integral value multiplier set the Nth-order time
integral value of the torque command to be a 1st-order time integral
value of the torque command.

[0039]Moreover, a fifth aspect of the invention is directed to the system
identification device according to the first or second aspect of the
invention, wherein the position amplitude calculator calculates a
position fundamental frequency component to be the fundamental frequency
component of the position, and then calculates and outputs the position
amplitude using a Fourier transformation,

[0040]the position torque command integral value multiplier calculates a
position fundamental frequency component to be the fundamental frequency
component of the position and a torque command fundamental frequency
component to be the fundamental frequency component of the torque command
using the Fourier transformation, and then calculates and outputs the
position torque command integral value multiplication value to be a
multiplication value of the position fundamental frequency component and
an Nth-order time integral value of the torque command fundamental
frequency component, and

[0041]the speed torque command integral value multiplier calculates a
torque command fundamental frequency component to be the fundamental
frequency component of the torque command and a speed fundamental
frequency component to be the fundamental frequency component of the
speed using the Fourier transformation, and then calculates and outputs
the speed torque command integral value multiplication value to be a
multiplication value of the Nth-order time integral value of the torque
command fundamental frequency component and the speed fundamental
frequency component.

[0042]Furthermore, a sixth aspect of the invention is directed to the
system identification device according to the first or second aspect of
the invention, wherein the position amplitude calculator calculates a
position fundamental frequency component to be the fundamental frequency
component of the position, and then calculates and outputs the position
amplitude using a band-pass filter,

[0043]the position torque command integral value multiplier calculates a
position fundamental frequency component to be the fundamental frequency
component of the position and a torque command fundamental frequency
component to be the fundamental frequency component of the torque command
using the band-pass filter, and then calculates and outputs the position
torque command integral value multiplication value to be a multiplication
value of the position fundamental frequency component and an Nth-order
time integral value of the torque command fundamental frequency
component, and

[0044]the speed torque command integral value multiplier calculates a
torque command fundamental frequency component to be the fundamental
frequency component of the torque command and a speed fundamental
frequency component to be the fundamental frequency component of the
speed using the band-pass filter, and then calculates and outputs the
speed torque command integral value multiplication value to be a
multiplication value of the Nth-order time integral value of the torque
command fundamental frequency component and the speed fundamental
frequency component.

[0045]In addition, a seventh aspect of the invention is directed to a
system identification device comprising:

[0046]a speed command generator for outputting a speed command;

[0047]a differentiator for inputting a position of an electric motor
detected by a position detector and then outputting a speed;

[0048]a speed controller for inputting the speed command and the speed and
then outputting a torque command;

[0049]a torque controller for inputting the torque command and then
driving the electric motor with an electric motor current; and

[0050]an inertia moment and viscous friction identifier for inputting the
torque command, the position and the speed, and then calculating and
outputting identification values of an inertia moment in the electric
motor and a viscous friction,

[0052]a position amplitude calculator for inputting the position and then
calculating and outputting a position amplitude to be an amplitude of a
fundamental frequency component of the input signal; and

[0053]a second inertia moment and viscous friction calculator for
inputting the position amplitude and the torque command, and calculating
a Fourier coefficient of the torque command by a Fourier transformation,
and then calculating and outputting the identification values of the
inertia moment and the viscous friction using the position amplitude and
the Fourier coefficient.

[0054]Moreover, an eighth aspect of the invention is directed to a system
identification device comprising:

[0055]a position command generator for outputting a position command;

[0056]a differentiator for inputting a position of an electric motor
detected by a position detector and then outputting a speed;

[0057]a position controller for inputting the position command and the
position and then outputting a speed command;

[0058]a speed controller for inputting the speed command and the speed and
then outputting a torque command;

[0059]a torque controller for inputting the torque command and then
driving the electric motor with an electric motor current; and

[0060]an inertia moment and viscous friction identifier for inputting the
torque command, the position and the speed, and then calculating and
outputting identification values of an inertia moment in the electric
motor and a viscous friction,

[0062]a position amplitude calculator for inputting the position and then
calculating and outputting a position amplitude to be an amplitude of a
fundamental frequency component of the input signal; and

[0063]a second inertia moment and viscous friction calculator for
inputting the position amplitude and the torque command, and calculating
a Fourier coefficient of the torque command by a Fourier transformation,
and then calculating and outputting the identification values of the
inertia moment and the viscous friction using the position amplitude and
the Fourier coefficient.

[0064]Furthermore, a ninth aspect of the invention is directed to the
system identification device according to the first aspect of the
invention, wherein when a fundamental frequency of the speed command is
represented by ω, a torque command fundamental frequency component
is represented by Tref0, a position fundamental frequency component is
represented by θ0, and the position amplitude is represented by A,

[0065]the first inertia moment and viscous friction calculator calculates
the identification values of the inertia moment J in the electric motor
and the viscous friction D in accordance with the following Equations (1)
and (2):

[0066]In addition, a tenth aspect of the invention is directed to the
system identification device according to the second aspect of the
invention, wherein when a fundamental frequency of the position command
is represented by ω, a torque command fundamental frequency
component is represented by Tref0, a position fundamental frequency
component is represented by θ0, and the position amplitude is
represented by A,

[0067]the first inertia moment and viscous friction calculator calculates
the identification values of the inertia moment J in the electric motor
and the viscous friction D in accordance with the following Equations (1)
and (2):

[0068]Moreover, an eleventh aspect of the invention is directed to the
system identification device according to the first aspect of the
invention, wherein

[0069]when a fundamental frequency of the speed command is represented by
ω, a torque command fundamental frequency component is represented
by Tref0, a position fundamental frequency component is represented by
θ0, and the position amplitude is represented by A,

[0070]the first inertia moment and viscous friction calculator calculates
the identification values of the inertia moment J in the electric motor
and the viscous friction D in accordance with the following Equations (3)
and (4):

[0071]Furthermore, a twelfth aspect of the invention is directed to the
system identification device according to the second aspect of the
invention, wherein

[0072]when a fundamental frequency of the position command is represented
by ω, a torque command fundamental frequency component is
represented by Tref0, a position fundamental frequency component is
represented by θ0, and the position amplitude is represented by A,

[0073]the first inertia moment and viscous friction calculator calculates
the identification values of the inertia moment J in the electric motor
and the viscous friction D in accordance with the following Equations (3)
and (4):

[0074]In addition, a thirteenth aspect of the invention is directed to the
system identification device according to the seventh aspect of the
invention, wherein

[0075]when a fundamental frequency of the speed command is represented by
ω, the position amplitude is represented by A, a Fourier
coefficient of a fundamental frequency cosine component of the torque
command is represented by a0, and a Fourier coefficient of a fundamental
frequency sine component of the torque command is represented by b0,

[0076]the second inertia moment and viscous friction calculator calculates
the identification values of the inertia moment J in the electric motor
and the viscous friction D in accordance with the following Equations (5)
and (6):

J = - a 0 ω 2 A ( 5 ) D = - b 0
ω A ( 6 ) ##EQU00005##

[0077]Moreover, a fourteenth aspect of the invention is directed to the
system identification device according to the eighth aspect of the
invention, wherein

[0078]when a fundamental frequency of the speed command is represented by
ω, the position amplitude is represented by A, a Fourier
coefficient of a fundamental frequency cosine component of the torque
command is represented by a0, and a Fourier coefficient of a fundamental
frequency sine component of the torque command is represented by b0,

[0079]the second inertia moment and viscous friction calculator calculates
the identification values of the inertia moment J in the electric motor
and the viscous friction D in accordance with the following Equations (5)
and (6):

J = - a 0 ω 2 A ( 5 ) D = - b 0
ω A ( 6 ) ##EQU00006##

ADVANTAGE OF THE INVENTION

[0080]According to the first aspect of the invention, it is possible to
suppress the influence of a constant torque disturbance and to identify
an inertia moment in an electric motor and a viscous friction through
only a very small operation in a speed control system having any linear
control law.

[0081]According to the second aspect of the invention, moreover, it is
possible to suppress the influence of a constant torque disturbance and
to identify an inertia moment in an electric motor and a viscous friction
through only a very small operation in a position control system having
any linear control law.

[0082]According to the third, ninth and tenth aspects of the invention,
furthermore, it is possible to suppress the influence of a constant
torque disturbance and to identify an inertia moment in an electric motor
and a viscous friction through only a very small operation for any linear
control law using any periodic speed command or periodic position
command.

[0083]According to the fourth, eleventh and twelfth aspects of the
invention, moreover, it is possible to suppress the influence of a
constant torque disturbance, to control the influence of a noise in a
torque command and to identify an inertia moment in an electric motor and
a viscous friction through only a very small operation for any linear
control law using any periodic speed command or periodic position
command.

[0084]According to the fifth and sixth aspects of the invention,
furthermore, it is possible to suppress the influence of a constant
torque disturbance and to identify an inertia moment in an electric motor
and a viscous friction through only a very small operation in a short
time for any linear control law using an optional periodic speed command
or periodic position command.

[0085]According to the seventh, eighth, thirteenth and fourteenth aspects
of the invention, moreover, it is possible to suppress the influence of a
constant torque disturbance and to identify an inertia moment in an
electric motor and a viscous friction through only a very small operation
in a short time for any linear control law using any periodic speed
command or periodic position command through only a simple calculation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0086]FIG. 1 is a block diagram showing a system identification device
according to a first example;

[0087]FIG. 2 is a detailed block diagram showing an inertia moment and
viscous friction identifier in the system identification device according
to the first example;

[0088]FIG. 3 is a block diagram showing a system identification device
according to a second example;

[0089]FIGS. 4A and 4B are charts showing simulation results, where a net
value of an inertia moment is varied in the system identification device
according to the second example;

[0090]FIGS. 5A and 5B are charts showing simulation results, where a net
value of a viscous friction is varied in the system identification device
according to the second example;

[0091]FIGS. 6A and 6B are charts showing simulation results, where a
constant torque disturbance is changed in the system identification
device according to the second example;

[0092]FIG. 7 is a detailed block diagram showing an inertia moment and
viscous friction identifier in a system identification device according
to a fourth example; and

[0093]FIG. 8 is a block diagram showing a system identification device
according to the related art.

[0121]A structure of the system identification device in the first example
will be described below with reference to FIG. 1.

[0122]The speed command generator 101 outputs a speed command. The speed
controller 102 inputs the speed command and a speed and then outputs a
torque command. The torque controller 103 inputs the torque command and
then outputs an electric motor current. The electric motor 104 is driven
with the electric motor current and the position detector 105 detects and
outputs a position thereof. The differentiator 106 inputs the position
and then outputs the speed. The inertia moment and viscous friction
identifier 107 inputs the torque command, the position and the speed, and
then calculates and outputs identification values of inertia moment and
viscous friction to be an inertia moment in the electric motor 104 and a
viscous friction.

[0123]FIG. 2 is a detailed block diagram showing an inertia moment and
viscous friction identifier in the system identification device according
to the first example.

[0125]First of all, the detailed structure of the inertia moment and
viscous friction identifier 107 according to the first example will be
described with reference to FIG. 2. The position amplitude calculator 201
inputs a position and then calculates and outputs a position amplitude to
be a fundamental frequency component amplitude of the input signal. The
position torque command integral value multiplier 202 inputs the position
and a torque command and then calculates and outputs a position torque
command integral value multiplication value to be a multiplication value
of fundamental frequency component of the position and a 0th-order time
integral value of the torque command. The position torque command
integral value average calculator 203 inputs the position torque command
integral value multiplication value and then calculates and outputs an
average of position torque command integral value to be a one-cycle
average of the input signal. The speed torque command integral value
multiplier 204 inputs the torque command and a speed and then calculates
and outputs a speed torque command integral value multiplication value to
be a multiplication value of fundamental frequency component of the speed
and a 0th-order time integral value of the torque command. The speed
torque command integral value average calculator 205 inputs the speed
torque command integral value multiplication value and then calculates
and outputs an average of speed torque command integral value to be a
one-cycle average of the input signal. The first inertia moment and
viscous friction calculator 206 inputs the position amplitude, the
average of position torque command integral value and the average of
speed torque command integral value and then calculates and outputs
identification values of inertia moment and viscous friction to be an
inertia moment in the electric motor 104 and a viscous friction.

[0126]Next, the principle of the inertia moment and viscous friction
identifier 107 according to the first example will be described with
reference to FIGS. 1 and 2.

[0127]An equation of motion of an open loop system including the torque
controller 103, the electric motor 104 and the position detector 105 is
represented by Equation (7), where an inertia moment of the electric
motor 104 is represented by J, a viscous friction is represented by D, a
torque command is represented by Tref, a constant torque disturbance is
represented by w and a position is represented by θ.

J{umlaut over (θ)}+D{dot over (θ)}=Tref-w (7)

[0128]When a speed command is set to be a sine wave having a frequency
ω, the position is also the sine wave having the frequency ω
in a steady state and is represented by Equation (8).

θ=A cos ωt (8)

[0129]In this case, A represents a position amplitude.

[0130]The Equation (8) is substituted for the Equation (7) to carry out a
calculation for the torque command so that Equation (9) is obtained.

[0131]The position torque command integral value multiplication value
output from the position torque command integral value multiplier 202 is
represented by Equation (10) based on the Equations (8) and (9).

[0134]The viscous friction D is represented by Equation (13) using an
average of speed torque command integral value to be a one-cycle average
in the Equation (12).

D = 2 T ref θ . _ ω 2 A 2 ( 13
) ##EQU00011##

[0135]The first inertia moment and viscous friction calculator 206 can
calculate identification values of inertia moment and viscous friction to
be the inertia moment J in the electric motor 104 and the viscous
friction D using the Equations (11) and (13).

[0136]The Equations (11) and (13) do not contain the constant torque
disturbance w. Therefore, the constant torque disturbance w does not
influence the identification values of inertia moment and viscous
friction.

[0137]Next, an operation of the inertia moment and viscous friction
identifier 107 according to the first example will be described with
reference to FIGS. 1 and 2.

[0138]The position amplitude calculator 201 calculates a position
fundamental frequency component to be a fundamental frequency component
of the position and then calculates and outputs the position amplitude to
be an amplitude thereof using a Fourier transformation or a band-pass
filter. The position torque command integral value multiplier 202
calculates a position fundamental frequency component to be a fundamental
frequency component of the position and a torque command integral value
fundamental frequency component to be a fundamental frequency component
of a 0th-order time integral value of the torque command using the
Fourier transformation or the band-pass filter, and then calculates and
outputs the position torque command integral value multiplication value
to be a multiplication value of the position fundamental frequency
component and the torque command integral value fundamental frequency
component. The speed torque command integral value multiplier 204
calculates a torque command integral value fundamental frequency
component to be a fundamental frequency component of a 0th-order time
integral value of the torque command and a speed fundamental frequency
component to be a fundamental speed component of the speed using the
Fourier transformation or the band-pass filter, and then calculates and
outputs the speed torque command integral value multiplication value to
be a multiplication value of the torque command integral value
fundamental frequency component and the speed fundamental frequency
component. The first inertia moment and viscous friction calculator 206
can calculate the identification values of the inertia moment and the
viscous friction for any periodic speed command by setting the torque
command Tref in the Equations (11) and (13) as a torque command
fundamental frequency component and setting the position 8 as the
position fundamental frequency component.

[0139]Thus, the system identification device according to the first
example uses a position amplitude, an average of position torque command
integral value and an average of speed torque command integral value. In
a speed control system having any linear control law, therefore, it is
possible to suppress the influence of a constant torque disturbance and
to identify an inertia moment in an electric motor and a viscous friction
through only a very small operation.

Second Example

[0140]FIG. 3 is a block diagram showing a system identification device
according to a second example.

[0142]A structure of the system identification device according to the
second example will be described below with reference to FIG. 3.

[0143]The position command generator 301 outputs a position command. The
position controller 302 inputs the position command and a position and
then outputs a speed command. The speed controller 102 inputs the speed
command and a speed and then outputs a torque command. The torque
controller 103 inputs the torque command and then outputs an electric
motor current. The electric motor 104 is driven with the electric motor
current, and the position is detected and output by the position detector
105. The differentiator 106 inputs the position and then outputs the
speed. The inertia moment and viscous friction identifier 107 inputs the
torque command, the position and the speed and then calculates and
outputs identification values of inertia moment and viscous friction of
the inertia moment in the electric motor 104 and the viscous friction.

[0144]Since a structure of the inertia moment and viscous friction
identifier 107 according to the example is the same as that of the first
example, description will be omitted.

[0145]A simulation result according to the second example will be
described below.

[0146]Numeric values used in the simulation are represented by Equation
(14).

Jm=0.116×10-4 kgm2, J1=0.8164×10-4
kgm2, J=Jm+J1

D*=0.001Nms/rad, Trat=0.637Nm

Kp=40 rad/s, Kv=40 (2π)rad/s, Kvj=KvJm

T=125×10-6s, u0=0.01rad, ω=1(2π)rad/s, w=0 Nm
(14)

[0147]It is assumed that the electric motor 104 is obtained by applying a
rigid load to an electric motor, Jm denotes an electric motor inertia
moment, J1 denotes a load inertia moment, J* denotes a net value of an
inertia moment of the electric motor 104, D* denotes a net value of a
viscous friction, Trat denotes a rated torque, T denotes a control cycle,
w denotes a constant torque disturbance, and the position controller 302
is set to be a proportional control having a gain of Kp, the speed
controller 102 is set to be a proportional control having a gain of Kvj,
and a position command is set to be a sine wave having a frequency of
ω and an amplitude of u0.

[0148]FIGS. 4A and 4B are charts showing simulation results, where a net
value of an inertia moment is varied in the system identification device
according to the second example. FIG. 4A shows an inertia moment
identification error eJ calculated in accordance with Equation (15),
where a load inertia moment is varied. FIG. 4B shows a viscous friction
identification error eD calculated in accordance with Equation (16),
where the load inertia moment is varied.

[0150]In FIGS. 4A and 4B, when a ratio J1/Jm of the load inertia moment to
an electric motor inertia moment is changed from 0% to 10,000%, the
inertia moment identification error is 0.6% or less and the viscous
friction identification error is 1% or less. The inertia moment
identification error shown in FIG. 4A is increased with a decrease in the
load inertia moment because a denominator in the Equation (15) is
reduced.

[0151]FIGS. 5A and 5B are charts showing a simulation result where a net
value of a viscous friction is varied in the system identification device
according to the second example. FIG. 5A shows an inertia moment
identification error eJ calculated in accordance with the Equation (15),
where a viscous friction is varied. FIG. 5B shows a viscous friction
identification error eD calculated in accordance with the Equation (16),
where the viscous friction is varied. In FIG. 5A, when the viscous
friction is changed from 0N*m*s/rad to 0.01N*m*s/rad, the inertia moment
identification error is 1% or less. In FIG. 5B, when the viscous friction
is changed from 0.001N*m*s/rad to 0.01N*m*s/rad, the viscous friction
identification error is 0.06% or less. The viscous friction
identification error is increased with a decrease in the viscous friction
because a denominator in the Equation (16) approximates to zero.

[0152]FIGS. 6A and 6B are charts showing simulation results, where a
constant torque disturbance is varied in the system identification device
according to the second example. FIG. 6A shows the inertia moment
identification error eJ calculated in accordance with the Equation (15),
where the constant torque disturbance is varied. FIG. 6B shows the
viscous friction identification error eD calculated in accordance with
the Equation (16), where the constant torque disturbance is varied.

[0153]In FIGS. 6A and 6B, when a ratio w/Trat of the constant torque
disturbance to a rated torque is changed from 0% to 50%, the inertia
moment identification error is 0.07% or less and the viscous friction
identification error is 0.07% or less.

[0154]In the simulation, a position amplitude is always equal to or
smaller than 0.02 rad (417 pulses in a 17-bit encoder).

[0155]Thus, the system identification device according to the second
example uses the position amplitude, the average of position torque
command integral value and the average of speed torque command integral
value. In a position control system having any linear control law,
therefore, it is possible to suppress the influence of a constant torque
disturbance and to identify an inertia moment in an electric motor and a
viscous friction through only a very small operation.

Third Example

[0156]The third example is different from the first and second examples in
that the third example employs a structure in which a position torque
command integral value multiplier 202 and a speed torque command integral
value multiplier 204 use a 1st-order time integral value of a torque
command in place of a 0th-order time integral value of the torque
command. Since other structures are the same as those in the first and
second examples, description thereof will be omitted.

[0157]First of all, the principle of the example will be described with
reference to FIGS. 1, 2 and 3.

[0158]An equation of motion of an open loop system including a torque
controller 103, an electric motor 104 and a position detector 105 is
represented by the Equation (7) according to the first example, where an
inertia moment of the electric motor 104 is represented by J, a viscous
friction is represented by D, a torque command is represented by Tref, a
constant torque disturbance is represented by w and a position is
represented by θ. When the speed command or the position command is
set to be a sine wave having a frequency of ω, the position is also
the sine wave having the frequency of ω in a steady state and is
represented by the Equation (8) according to the first example. The
Equation (8) is substituted for the Equation (7) to carry out a
calculation for the torque command so that the Equation (9) is obtained.
A torque command integral value to be a 1st-order time integral value in
the Equation (9) is represented by Equation (17).

∫Trefdt=ωAJ sin ωt+AD cos ωt+wt (17)

[0159]The position torque command integral value multiplication value is
obtained by multiplying the Equations (8) and (17) so that Equation (18)
is obtained.

[0163]Using the one-cycle average in the Equation (20), the moment of
inertia J of the electric motor 104 is obtained by Equation (21).

J = 2 ∫ T ref t θ . _ ω
2 A 2 ( 21 ) ##EQU00016##

[0164]The first inertia moment and viscous friction calculator 206 can
calculate identification values of inertia moment and viscous friction to
be the viscous friction D and the moment of inertia J in the electric
motor 104 using the Equations (19) and (21). The Equations (19) and (21)
do not contain the constant torque disturbance w. Therefore, the constant
torque disturbance w does not influence the identification values of
inertia moment and viscous friction. When the torque command includes a
noise, a waveform of the torque command integral value is smoother than
that of the torque command. By using the Equations (19) and (21), it is
possible to suppress the influence of the noise on the identification
values of inertia moment and viscous friction.

[0165]Next, an operation according to the third example will be described
with reference to FIGS. 1 to 3.

[0166]A position amplitude calculator 201 calculates a position
fundamental frequency component to be a fundamental frequency component
of the position and then calculates and outputs the position amplitude to
be an amplitude thereof using a Fourier transformation or a band-pass
filter. The position torque command integral value multiplier 202
calculates a position fundamental frequency component to be a fundamental
frequency component of the position and a torque command integral value
fundamental frequency component to be a fundamental frequency component
of a 1st-order time integral value of the torque command using the
Fourier transformation or the band-pass filter, and then calculates and
outputs the position torque command integral value multiplication value
to be a multiplication value of the position fundamental frequency
component and the torque command integral value fundamental frequency
component. The speed torque command integral value multiplier 204
calculates a torque command integral value fundamental frequency
component to be a fundamental frequency component of a 1st-order time
integral value of the torque command and a speed fundamental frequency
component to be a fundamental frequency component of the speed using the
Fourier transformation or the band-pass filter, and then calculates and
outputs the speed torque command integral value multiplication value to
be a multiplication value of the torque command integral value
fundamental frequency component and the speed fundamental frequency
component. The first inertia moment and viscous friction calculator 206
can calculate the identification values of inertia moment and viscous
friction for any periodic speed command or periodic position command by
setting the torque command Tref in the Equations (19) and (21) as a
torque command fundamental frequency component and setting the position
θ as the position fundamental frequency component.

[0167]Even when an Nth-order time integral value of the torque command is
used in place of the 1st-order time integral value of the torque command,
wherein N is set to a natural number including zero; that is, even when
the position torque command integral value multiplier 202 is constituted
to calculate and output a position torque command integral value
multiplication value to be a multiplication value of fundamental
frequency component of the position and the Nth-order time integral value
of the torque command when the position and the torque command are input
and N is set to the natural number including zero, and the speed torque
command integral value multiplier 204 is constituted to calculate and
output a speed torque command integral value multiplication value to be a
multiplication value of fundamental frequency component of the speed and
the Nth-order time integral value of the torque command when the torque
command and the speed are input and N is set to be the natural number
including zero; the first inertia moment and viscous friction calculator
206 can calculate the identification values of the inertia moment and the
viscous friction in the same manner as in the example.

[0168]Thus, the system identification device according to the third
example uses a position amplitude, an average of position torque command
integral value and an average of speed torque command integral value.
Therefore, it is possible to suppress the influence of a constant torque
disturbance and to control the influence of a noise in a torque command,
thereby identifying an inertia moment in an electric motor and a viscous
friction through only a very small operation.

Fourth Example

[0169]FIG. 7 is a detailed block diagram showing an inertia moment and
viscous friction identifier in a system identification device according
to a fourth example.

[0170]In FIG. 7, 201 denotes a position amplitude calculator and 701
denotes a second inertia moment and viscous friction calculator.

[0171]The fourth example is different from the first, second and third
examples in that an inertia moment and viscous friction identifier 107
according to the fourth example is constituted by: a position amplitude
calculator 201 for inputting the position and then calculating and
outputting a position amplitude to be a fundamental frequency component
amplitude of the input signal; and a second inertia moment and viscous
friction calculator 701 for inputting the position amplitude and the
torque command, and then calculating a Fourier coefficient of the torque
command through a Fourier transformation and then calculating and
outputting the identification values of the inertia moment and the
viscous friction by using the position amplitude and the Fourier
coefficient.

[0172]A principle and operation according to the invention will be
described below with reference to FIGS. 1, 3 and 7.

[0173]The position amplitude calculator 201 calculates a position
fundamental frequency component represented by Equation (22) using the
Fourier transformation.

θ0=A cos ωt (22)

[0174]Here, A denotes the position amplitude and ω denotes a
fundamental frequency of the speed command or the position command.

[0178]Equation (25) is obtained from a one-cycle average of the Equation
(24).

T ref 0 θ 0 _ = a 0 A 2 ( 25 )
##EQU00018##

[0179]Using the Equation (25), an inertia moment J of an electric motor
104 is obtained in accordance with Equation (26) in FIG. 1 or 3 in the
same manner as in the Equation (11) according to the first example.

[0181]Equation (28) is obtained from a one-cycle average of the Equation
(27).

T ref 0 θ . 0 _ = - b 0 ω
A 2 ( 28 ) ##EQU00021##

[0182]A viscous friction D of the electric motor 104 is given by Equation
(29) using the Equation (28) in the same manner as in the Equation (13).

D = - b 0 ω A ( 29 ) ##EQU00022##

[0183]The second inertia moment and viscous friction calculator 701 can
calculate identification values of inertia moment and viscous friction to
be the inertia moment J in the electric motor 104 and the viscous
friction D using the Equations (26) and (29). The Equations (26) and (29)
do not include a constant torque disturbance w. Therefore, the constant
torque disturbance w does not influence the identification values of the
inertia moment and the viscous friction.

[0184]Thus, the system identification device according to the example uses
the Fourier coefficients of the position amplitude and the torque command
fundamental frequency component. Therefore, it is possible to identify
the inertia moment in an electric motor and the viscous friction through
only a very small operation in a short time while suppressing the
influence of a constant torque disturbance for any linear control law
through only a simple calculation using any periodic speed command or
periodic position command.

INDUSTRIAL APPLICABILITY

[0185]By using a position amplitude, an average of position torque command
integral value and an average of speed torque command integral value, it
is possible to identify an inertia moment in an electric motor and a
viscous friction through only a very small operation. Therefore, it is
possible to widely apply to apparatuses for general industry such as a
chip mounter.